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736

Hydraulic Press,

fc". 1

i

I?, i

while the pump leverage is L : i; from the principle of equal
transmission, one pound per sq. inch on the pump plunger is one
pound-per sq. inch on the ram, and

Total Mechanical Advantage

= Mech. Adv. of press and pump x leverage
area of press      L ___ D2 L
area of pump      i         d%

Neglecting friction.    Taking pump efficiency
= 76, and press efficiency = '95  both combined = 76 x '95 = "72

(Seep. 1210.)



The ram cylinder should be approximately hemispherical (see
p. 68), and its strength is found at p. 399. The leather collar E is
a most efficient packing, being distended by the pressure water
and pressed against the ram surface. The hydraulic jack, p. 206,
is simply a miniature press, where G is the ram and D the plunger.
Its efficiency is, of course, much higher than that of other jacks.

The Hydraulic Accumulator is probably the most im-
portant adjunct in hydraulic transmission, constituting an arti-
ficial head, in which the water pressure is caused by other material
than water. In Fig. 726, a series of weights at c hang from the